Choice Of Reference Value Research Articles

Mutual validation of remote hydraulic estimates and flow model simulations using UAV-borne LiDAR and deep learning-based imaging techniques

Hydraulic modeling plays a pivotal role in various river-related applications, but acquiring precise datasets can be challenging due to complex environments and limited availability of field data. To address these challenges, remote sensing approaches have shown promise, but their widespread scientific use requires validation. This study investigates the utilization of an uncrewed aerial vehicle (UAV)-integrated topo-bathymetric green LiDAR system (GLS) combined with deep learning-based space-time image velocimetry (DL-STIV) techniques to remotely analyze hydraulic properties in the lower Asahi River, Japan. The research compares streamflow measurements with flow model simulations at four transects within a 1.2 km gravel bed channel with vegetation. The results demonstrate that the DL-STIV technique provides reliable velocity estimates, with root-mean-square errors ranging from 0.014 to 0.247 m/s. When using a typical velocity conversion factor of 0.85, the DL-STIV method aligns well with model predictions, yielding coefficient of determination values between 0.850 and 0.959. However, the choice of conversion index (ranging from 0.75 to 0.95) significantly affects accuracy. The study also reveals that remotely estimated discharges are reasonably consistent with model estimates, with errors ranging from 0.026 to 11.124%. However, accuracy is influenced by factors such as the presence of obstacles, uncertainties in remotely sensed water depths, and the choice of reference values. In conclusion, this research demonstrates the suitability and potential of GLS and DL-STIV for remotely analyzing hydraulic properties in rivers. The study also points to the importance of considering potential variations and uncertainties when adopting these techniques for flow modeling and validation purposes.

Spirometry: how to evaluate the results?

Introduction. The European Respiratory Society, the American Thoracic Society, and the Russian Respiratory Society are currently working on updating the technical standards and interpretive strategies for routine lung function tests. There is a search for recommendations for the best choice of reference values, the optimal limits of normal and severity grading of detected impairments. An important step in this work is the standartization of pulmonary function tests interpretation, including spirometry. Aim. Review of existing concepts for the spirometry interpretation, according to new approaches to their quantitative and qualitative assessment. Materials and methods. The scientific publications on the PubMed and eLIBRARY.RU platforms were analyzed. The materials posted on the official websites of the European Respiratory Society, the Russian Respiratory Society, the American Thoracic Society and the Global Lung Function Initiativewere also used. Results. A brief overview of the main reference values for spirometry is presented: the European Coal and Steel Community (1993), Global Lung Function Initiative (2012, 2021), R.F.Klement et al. (1986, 1991). The issues of defining the lower limit of the normal, diagnosing ventilatory impairments and assessing the severity of lung function reduction using the z-score and a percentage of the predicted value when analyzing the results of spirometry are considered. Conclusion. The type of ventilatory impairment and severity should be presented in the spirometry interpretation just like the vital capacity assessment. The obstructive ventilatory impairment is generally diagnosed by spirometry, if the signs of restrictive or mixed patterns are present, it is recommended to determine the total lung capacity by body plethysmographymethod. Assessment of the limits of normal and the severity levels for any spirometry indices should be carried out using the z-score values.

Universal features of particle motion in ac electric fields

Mobile particles present as contaminants in high voltage gas insulated switchgear (GIS) may constitute a risk for insulation failure. The understanding of their motion in the electric field of the insulation gap is therefore essential for quality control in manufacturing, commissioning and in service monitoring. Published research on particle motion in ac electric fields has shown that this rather complex process depends on numerous parameters, many of which remain unknown under practical conditions. This renders modelling, generalization of experimental data and practical application difficult. The scope of this paper therefore is to develop a unified description of particle motion which minimizes the number of controlling parameters, enables the comparison of experimental data and allows simple interpretation relations to be derived. This is achieved by making the controlling equations dimensionless with an appropriate choice of reference values and by using simplifying assumptions for the specific conditions prevailing in GIS. The resulting generalized description of the process can then be summarized in the form of 2D patterns (dynamic maps). Approximate scaling relations are derived between specific features of these patterns and particle-related parameters. A reference case is discussed in detail. The non-linear character of the equation of motion suggests that the particle motion may be a deterministic process with chaotic features. This is confirmed by a preliminary chaos-theoretical analysis of the process.

Application of the maximum cumulative ratio (MCR) as a screening tool for the evaluation of mixtures in residential indoor air

The maximum cumulative ratio (MCR) method allows the categorisation of mixtures according to whether the mixture is of concern for toxicity and if so whether this is driven by one substance or multiple substances. The aim of the present study was to explore, by application of the MCR approach, whether health risks due to indoor air pollution are dominated by one substance or are due to concurrent exposure to various substances. Analysis was undertaken on monitoring data of four European indoor studies (giving five datasets), involving 1800 records of indoor air or personal exposure.Application of the MCR methodology requires knowledge of the concentrations of chemicals in a mixture together with health-based reference values for those chemicals. For this evaluation, single substance health-based reference values (RVs) were selected through a structured review process.The MCR analysis found high variability in the proportion of samples of concern for mixture toxicity. The fraction of samples in these groups of concern varied from 2% (Flemish schools) to 77% (EXPOLIS, Basel, indoor), the variation being due not only to the variation in indoor air contaminant levels across the studies but also to other factors such as differences in number and type of substances monitored, analytical performance, and choice of RVs. However, in 4 out of the 5 datasets, a considerable proportion of cases were found where a chemical-by-chemical approach failed to identify the need for the investigation of combined risk assessment.Although the MCR methodology applied in the current study provides no consideration of commonality of endpoints, it provides a tool for discrimination between those mixtures requiring further combined risk assessment and those for which a single-substance assessment is sufficient.

Flow Variability in a North American Downtown Street Canyon

Abstract Previous field and laboratory studies have indicated that flow and turbulence inside urban areas and, in particular, in street canyons, is very complex and is associated with wakes and vortices developing near buildings. However, a number of open questions still exist, primarily with regard to which parameters determine the structure of street-canyon flow. The paper presents results from high-resolution wind measurements in a downtown urban street canyon in Oklahoma City, Oklahoma, that were conducted during the Joint Urban 2003 tracer experiment. Data collected with sonic anemometers on two towers installed on opposite sites of the street canyon, each with five different measurement levels, have been analyzed, and the variation of in-canyon flow and turbulence parameters with wind direction and atmospheric stability is discussed. It was found that the street-canyon flow is strongly channeled and its direction is determined by the along-canyon component of the above-roof-level winds. As a consequence, the direction of the street-level winds changes abruptly, and small variations of the upwind direction can significantly alter the in-canyon flow properties. Contrary to results from studies with idealized street canyons, the along-canyon flow components remained significant even for conditions with winds approaching the street at almost perpendicular angles. For such wind directions, a tendency toward development of street-canyon vortices with pronounced vertical motions have been found. However, the complex building geometries at the chosen measurement site enhance the complexity of the flow patterns, and situations with a classic street-canyon vortex rotating in the street could not be identified. In addition, the comprehensive dataset from the Joint Urban 2003 field campaign allowed detailed study of the influence of boundary layer stability on flow in the urban canopy layer. It has become clear that very different conclusions can be drawn with regard to these effects depending on the choice of reference values used in the analysis of the street-canyon data. Using winds from higher elevations in the atmospheric boundary layer (250 m) as reference data, one would conclude that atmospheric stability strongly influences in-canyon flow and, in particular, turbulence. However, only minor stability effects are still seen after normalization with wind speed values at average roof-level height (80 m). This choice allows one to conclude that the in-canyon flow is primarily driven by the boundary layer wind field at average roof level.